1. Field of the Invention
In one aspect, this invention relates to tire inflation valves. In a further aspect, this invention relates to pressure change indicators.
2. Description of the Prior Art
An example of a combination tire pressure inflator and pressure change indicating device is shown in U.S. Pat. Nos. 3,800,736 and 3,910,223. In the known device, there are two chambers. One chamber provides a reference pressure, and the other chamber monitors the tire's internal pressure. When a pressure differential exists between the chambers, an indicator is activated which warns that the tire's internal pressure is low.